It is often desirable to detect moving objects, animals or individuals, for instance, in a security system in a building. Sensors in these security systems have typically used infrared or ultrasound energy to detect motion. It is well known that such sensors often have coverage limitations that make it difficult to insure reliable detection or may have false alarm rates that are unacceptable.
As described in the referenced patent application “Method and Apparatus for Through-the-Wall Motion Detection Utilizing CW Radar,” the use of CW radar enables motion detection through walls and other obstacles and is therefore less susceptible to the limitations of infrared and ultrasonic motion sensors.
Furthermore, it may be useful to have a sensor that communicates with a central station without using wires as disclosed in the referenced patent application “Combined Radar and Communications Link.”
CW radar sensors by themselves, however, may have their own limitations such as relatively high power drain and a relatively high false alarm rate.
What is therefore required is a low cost, ultra-low power drain, wireless, compact remotely operated unit that can detect motion of objects, animals or individuals with a reduced false alarm rate.
More particularly, one can utilize a CW radar to sense movement behind a wall or in fact movement anywhere. When these CW movement detection radars are utilized and are battery-powered, they draw a considerable amount of current. Thus CW radar is not useful for long-term surveillance applications. For instance, such CW radar surveillance units, when utilizing a couple of double-A batteries, might last 12 hours before the batteries run out.
Moreover, due to the relatively sensitive nature of the phase detection used in detecting motion for these CW radars, one would like to have an independent confirmation that motion is occurring so as to minimize the high false alarm rates associated with some CW radars.
Thus, at the very least there is a requirement to be able to provide long-term surveillance utilizing a battery-powered CW radar and to eliminate some of the problems due to false alarming.
Moreover, if numbers of CW radar sensors are used to track a moving object, the combined power drain would not be compatible with long-term surveillance applications.
Additionally, while movement can be determined by the use of CW radars, there may need to be classification of the type of moving target detected.